Control of the Inflammatory Macrophage Transcriptional Signature by miR-155

PLoS One. 2016 Jul 22;11(7):e0159724. doi: 10.1371/journal.pone.0159724. eCollection 2016.


Inflammatory M1 spectrum macrophages protect from infection but can cause inflammatory disease and tissue damage, whereas alternatively activated/M2 spectrum macrophages reduce inflammation and promote tissue repair. Modulation of macrophage phenotype may be therapeutically beneficial and requires further understanding of the molecular programs that control macrophage differentiation. A potential mechanism by which macrophages differentiate may be through microRNA (miRNA), which bind to messenger RNA and post-transcriptionally modify gene expression, cell phenotype and function. We hypothesized that the inflammation-associated miRNA, miR-155, would be required for typical development of macrophage inflammatory state. miR-155 was rapidly up-regulated over 100-fold in inflammatory M1(LPS + IFN-γ), but not M2(IL-4), macrophages. Inflammatory genes Inos, Il1b and Tnfa and their corresponding protein or enzymatic products were reduced up to 72% in miR-155 knockout mouse M1(LPS + IFN-γ) macrophages, but miR-155 deficiency did not affect expression of the M2-associated gene Arg1 in M2(IL-4) macrophages. Additionally, a miR-155 oligonucleotide inhibitor efficiently suppressed Inos and Tnfa gene expression in wild-type M1(LPS + IFN-γ) macrophages. Comparative transcriptional profiling of unstimulated and M1(LPS + IFN-γ) macrophages derived from wild-type (WT) and miR-155 knockout (KO) mice revealed that half (approximately 650 genes) of the signature we previously identified in WT M1(LPS + IFN-γ) macrophages was dependent on miR-155. Real-Time PCR of independent datasets confirmed that miR-155 contributed to suppression of its validated mRNA targets Inpp5d, Tspan14, Ptprj and Mafb and induction of Inos, Il1b, Tnfa, Il6 and Il12. Overall, these data indicate that miR-155 plays an essential role in driving the inflammatory phenotype of M1(LPS+ IFN-γ) macrophages.

MeSH terms

  • Animals
  • Biomarkers
  • Gene Expression Profiling
  • Gene Expression Regulation*
  • Gene Knockout Techniques
  • Inflammation / genetics*
  • Inflammation / immunology
  • Inflammation / metabolism
  • Macrophage Activation / genetics
  • Macrophage Activation / immunology
  • Macrophages / immunology
  • Macrophages / metabolism*
  • Mice
  • MicroRNAs / genetics*
  • Phenotype
  • RNA Interference
  • RNA, Messenger / genetics
  • Transcriptome*


  • Biomarkers
  • MicroRNAs
  • Mirn155 microRNA, mouse
  • RNA, Messenger